AmsJep"r;Sarm-}       Tinctures  from  Fluid  Extracts.  447 
Examination  of  these  tables  shows  marked  differences  between 
the  relative  maximum  doses  of  fluid  extracts,  and  those  given  by 
manufacturers  for  their  products ;  and  it  should  be  noted  that  the 
manufacturers  named  fairly  agree,  in  many  cases,  as  to  maximum 
doses. 
If  the  contention  that  representative  tinctures  of  drugs  can  be 
properly  made  by  diluting  fluid  extracts  be  true,  it  logically  follows 
that  the  relative  dose  of  a  given  tincture  and  fluid  extract  should  be 
identical.  If  the  10  per  cent,  tincture  of  drug  A  has  the  dose  of 
sixty  minims,  the  100  per  cent,  fluid  extract  of  drug  A  should  have 
the  dose  of  six  minims,  the  difference  between  the  official  per  cent,  by 
weight  for  tinctures,  and  per  cent,  by  volume  for  fluid  extract  making 
no  material  difference.  The  dose  of  cinchona  tincture  being  30  to  120 
minims,  the  dose  of  the  fluid  extract  (being  about  five  times  as  strong) 
should  be  one-fifth  or  6  to  24  minims;  yet  we  find  the  dose  as 
usually  given  is  from  15  to  60  minims. 
If  dose  is  any  criterion  of  drug-strength  at  all,  it  follows  that  the 
dose  of  tincture  and  fluid  extract  should  be  relatively  the  same,  if 
the  latter  is  to  be  diluted  to  make  the  former;  otherwise  there  must 
be  a  certain  difference  between  the  proportion  and  the  kinds  of 
proximate  principles  in  the  drug-tincture,  as  compared  with  those 
in  the  extract-tincture  Practically,  it  seems  impossible,  save  in 
some  few  cases,  to  obtain  fluid  extracts  which  will  have  the  same 
relative  dose  as  the  drug-tincture,  for  the  actual  dose  of  a  fluid 
extract  is  not  of  necessity  its  relative  dose  compared  with  the  dose 
of  the  tincture  ;  and  if  this  be  so,  the  making  of  representative 
tinctures  from  fluid  extracts  is  impossible.  Manufacturers  of  fluid 
extracts  are  not  to  be  blamed  for  this ;  it  is  a  condition  of  drug- 
exhaustion  over  which  they  have  no  control.  In  the  making  of  fluid 
extracts,  manufacturers  may  exhaust  a  drug  of  all  its  soluble  proxi- 
mate principles,  obtaining  them  in  solution,  but  on  storing  the  fluid 
extract  for  a  time  before  selling,  which  is  always  done  (or  if  it  is  not 
done,  the  fluid  extract  precipitates  afterwards),  the  product  invariably 
yields,  through  certain  changes,  precipitates  of  proximate  principles 
more  or  less  voluminous  in  character,  and  more  or  less  valuable 
therapeutically.  These  are  removed  by  decantation  and  filtration 
by  the  manufacturer  before  the  product  is  sold. 
It  does  not  follow  that  fluid  extracts  so  treated  are  necessarily 
inferior,  they  may  be  of  excellent  quality  for  fluid  extracts,  but  they 
